Low-Temperature Ozone Sensors Based on Yb-Doped Urchin-like Hierarchical In₂O₃ Microspheres

As a highly oxidizing and toxic gas, ozone (O₃) poses significant hazards to human health and the environment even at low concentrations. Therefore, the development of ozone gas sensors that can operate stably at low temperatures while simultaneously exhibiting high response, fast response characteristics, excellent selectivity, and long-term stability remains a crucial challenge in the field of gas sensing. In this work, Pure In₂O₃ and Yb-doped urchin-like hierarchical In₂O₃ microspheres were successfully synthesized via a one-step hydrothermal method. The crystal structure, morphological features, elemental composition, and band structure of the as-prepared samples were systematically characterized by XRD, FESEM, TEM, HRTEM, XPS, and UV-vis spectroscopy. Gas-sensing tests demonstrated that Yb doping significantly enhanced the ozone-sensing performance of In₂O₃. Among all the samples, the 3%Yb-doped In₂O₃ sensor exhibited the best response toward 1 ppm ozone at 40 °C, reaching approximately 1015, which was about 11 times higher than that of pristine In₂O₃. Meanwhile, the sensor showed a response time of 172 s. In addition, the 3%Yb-doped In₂O₃ sensor exhibited good repeatability, excellent selectivity, and long-term stability. The excellent gas-sensing performance can be attributed to the electronic structure modulation and increased O_V-related oxygen defect component induced by Yb doping, as well as the enhanced gas diffusion and interfacial reaction capability provided by the urchin-like hierarchical structure.